Circuit breaker



y 1949- v w. L. BUTLER 2,475,308

0 IRCUIT BREAKER Filed Nov. 15, 1946 2 Sheets-Sheet 1 Inventor: WilliamLawrence Butler,

H is Attorney.

July 5, 1949. w. BUTLER 2,475,308

CIRCUIT BREAKER Filed NOV. 15, 1946 I 2 Sheets-Sheet 2 Inventor: WalhamLawrence. Butler,

by His Attorney Patented July 5, 1949 CIRCUIT BREAKER William LawrenceButler, Schenectady, N. Y., as- Signor to General Electric Company, acorporation of New York Application November 15, 1946, Serial No.710,138

1 Claim. 1

My invention relates to circuit breakers, and more particularly to newand improved manually operable current responsively tripped circuitbreakers of the type described in my Patent 2,230,713, issued February4, 1941.

It is a general object of my invention to provide a new and improvedcircuit breaker of the above type which is trip-free in its automaticoperation and which is durable, dependable and inexpensive tomanufacture.

"it is a further object of my invention to provide a new and improvedpush button operating mechanism for a circuit breaker actuating linkn88.

it is still another object of my invention. to provide a new andimproved reset means for an over-center current responsive trippingmechanism when used in conjunction with the circuit breaker of theforegoing description.

My invention is especially useful in. manually operable currentresponsively tripped circuit breakers used for the connection of thesmall rootors directly across a supply source without a startingresistor. These devices are of small physical dimensions and at thepresent time are used with motors up to 7 horsepower.

For more complete understanding of my in vention and a furtherappreciation of its various objects and advantages reference should nowbe had to the following detailed specification taken in conjunction withthe accompanying drawings, in which Fig. 1 is a front view of athree-phase motor starting switch embodying my invention; Fig. 2 is asectional view taken along the line i2 of Fig. 1 looking in thedirection of the arrows and showing the operating mechanism in its onposition; Fig. 3 is a side elevational view of the operating mechanismwith one of the lat eral supporting plates removed to show the mechanismin its automatic trip position; Fig. i is a view similar to Fig. 3showing the operating mechanism in its reset position; and Fig. 5 is anexploded perspective view of the switch mechanism with various partsbroken away and showing the mechanism in its manual off position.

Referring now to the drawings, my invention in the form shown comprisesa circuit-breaker mechanism mounted upon a base I0 made of any suitableelectric insulating material, such as a suitable molded insulatingcompound, the base IO serving as a support both for the switch contactsand for a switch actuating and releasing mechanism. The base l0 alongwith the mechanism mounted thereon is mounted in an enclosing casing llhaving a cover I2.

The base l0- has an irregular shape determined by convenience insupporting the various parts of the device.

By way of illustration I have shown my invention as applied to a threepole or three circuit motor starter, such as might be used with athreephase motor. As best illustrated in Figs. 1, 2 and 5, each of thethree circuits comprises a pair of fixed contacts l3 and it connected bysuitable conductors to terminals ill and 58, respectively, at oppositeends of the base it. In the center circuit (Fig. 2) the contact l3 andterminal are directly connected by a conductor iii. In each outsidecircuit there is included a series heater for the current responsivetripping mechanism, as in my prior Fatent 2.2%,713. Each contact it isconnected to the associated termit nal it by a conductor i Each pair offixed contacts it and M is ar ranged to be connected together by amovable bridging contact it. The three bridging contacts ii are mountedupon a common insulating cross arm it which is carried at the end of apivoted lever it. The pivoted lever, or switch member, it is part of aswitch actuating mecha-- nism which is mounted between two metallicsupporting plates 2? and 23 which extend up wardly in parallel spacedrelation from the base to substantially in alignment with the centerphase oi the breaker. The switch member 29 is mounted at one end on afixed pivot carried by the supporting plates and The pivoted lever 2i isformed 01" two parallel side rails spaced apart and connected togetherfor rigidity by channel-shaped sections, the unsupported end of thelever being provided with an extension carrying the movable cross arm2h.

The switch member or lever it is arranged to be moved between circuitopening and circuit closing positions by a toggle mechanism whichcomprises a pair of links 25 pivotally mounted at one end upon a fixedpivot it carried by the supporting plates 22 and 23, and a pair of links21 pivotally connected in parallel spaced relation to the ends of thelinks 25, as by a pin 28. The links 2l are pivotally connected at theiropposite ends to an intermediate point of the switch lever 2|, as byprojections 29 on the lever 2|. As best shown at Figs. 2, 3 and 4 a pairof overcenter toggle springs 30 is connected between the outer ends ofthe pin 28 and a pin 3| which is movable manually over-center withrespect to the fixed pivot pin 26.

The manually movable pin 3| to which one end of each over-center spring30 is connected is carried upon a pivoted actuating plate or lever 32.

The lever 32 is centrally positioned between the pivoted'links 23 and ispivotally mounted upon a fixed pivot 33 carried by the supporting plates22 and 23. To permit movement of the pivoted links 25 withoutinterference-by the fixed pivot pin 33, the links' 25 are slotted, as at34, and the pin 33 passes through the slots.

In order to move the actuating plate 32 upon its pivot 33 and thus tomove the line or action oi the toggle springs-33 over-center withrespect to the fixed pivot 26 for manual opening and closing operationof the breaker contacts, I provide a push button linkage comprising apair of rocker arms 35 pivotally mounted in parallel spaced relationupon the fixed pivot pin 23 and connected at opposite ends to a pair ofreciprocable push buttons 33 and 33a. The push buttons 33 and 33a extendthrough suitable apertures in the cover l2 oi. the metal enclosure II.The movable end oi. the actuating plate 32 is coupled to the rocker arms35 for movement by camming action as the rocker arms are oscillated bythe push buttons. For this purpose the rocker arms 35 are provided atone end with open ended slots 31 into which extends a transverse pin 33fixed upon one side of the actuating plate 32. The slots 31 aregenerally tangent to a circle having its center at the fixed pivot 33,and camming action between the slots 31 and the pin 33 amplifies theangular movement of the actuating lever 32 with respect to angularmovement of the rocker arms 35. The rocker arms 35 are also slottedcentrally in the direction of their length at 31a in order toaccommodate arcuate movement of the spring pin 3| on the plate 32.

For automatic tripping operation in response to excessive currentthrough the contacts, I provide a spring biased tripping arm andlatching mechanism substantially the same as shown and described in myPatent 2,337,713, issued February 4, 1941, upon an application filedOctober 5, 1939. This mechanism comprises a substantially L- shaped tripmember 43 pivotally mounted as a bell crank upon the fixed pivot 23 andhaving one end connected to a tension spring 4|. The spring 4| isarranged to pull the trip member 43 forcibly against the toggle pin 23,thereby to break the toggle and to move the line of action oi the togglesprings 33 over-center with respect to the fixed pivot 23. Normally,however, the pivoted trip member 40 is held in retracted positionagainst the force of the spring 4| by a latch lever 42 forming part of adouble latch lever mechanism such as that described in my foregoingPatent 2,230,713. As described in that patent, the latch lever 42 ismounted intermediate its ends upon a fixed pivot 43 so that one end isin latching relation to one end of the trip member 40. The opposite end01' the latch lever 42 comprises a portion 42a which extends laterallyto a position near the trip member 40 and engages a second latch lever44. The latch lever 42 is prevented by the latch lever 44 from moving toa position to release the trip member 40. The lever 42 is biased tolatch releasing position by a tension spring 45 connected between thelever 44 and one end of the lever 42. The latch lever 44 is pivotallymounted upon the fixed pivot 24 and is movable against the force of thespring 45 to release the latch lever 42.

For the purpose of moving the lever 44 to release the latching mechanismupon excessive current, each outside circuit of the circuit breaker isprovided with a thermal responsive tripping mechanism 43 heated by acurrent carrying heater (not shown). the heaters being connected inseries circuit relation in the outside circuits as in my foregoingpatents. Each tripping mechanism 43 comprises a generally L-shapedmounting bracket 41 of channel-shaped cross section having extendingtherefrom an angle bracket 43. AdJustably mounted upon the bracket 41there is provided a U-shaped thermal unit comprising a rigid L-shapedmounting strip 43 connected to a fiat bimetallic bar 53. The bimetallicmember 53 is movable into and out oi engagement with an arm 5| extendingfrom the side oi an over-center trip lever 52. The trip lever 52 isendowed with a snap action by means of an overcenter spring 53 connectedbetween the bracket 43 and the trip lever 52. Each over-center triplever 52 is provided with an inwardly projecting arm 53 extending towardthe center of the circuit breaker and into position to engage the latchlever 44. This construction of the thermal responsive tripping mechanismis described in greater detail and claimed in my Patent 2,318,987,issued May 11, 1943, upon an application filed June 19, 1942.

The pin 33 carried by the actuating plate 32 is so positioned that, whenthe actuating plate is' manually moved toward the switch openingposition to reset the breaker after an automatic tripping operation, thepin 33 engages the trip lever 40 and forces it back into latchingengagement with the latch lever 42. In this resetting movement the tripmember 43 first engages the portion 42a of the latch lever 42 androtates the latch'lever 42 to its latching position, as described in myforegoing Patent 2,230,713. When the latch lever 42 is so returned tothe latching position the latch spring 45 is stressed and tends toreturn the second latch lever 44 to its latching position. However, thespring 45 is unable, without further aid, to so return the second latchlever 44 when over-center trip levers 52 of the type herein describedare used, because the overcenter springs 54 of the trip levers 52 arenecessarily stronger than the latching spring 45. It is thereforenecessary to provide separate means operable upon resetting movement forreturning the over-center trip levers 52 to their initial position sothat the latching spring 45 can return the second latch 44 to itslatching position.

For the purpose of restoring the over-center trip levers 52 to theirnormal positions by resetting movement after an automatic trippingoperation has occurred, I provide a pair of reset levers 55 mountedexternally oi the support ing plates 22 and 23 upon fixed pivots 53.These levers are in position to engage the inwardly extending arms 53 ofthe over-center tripping levers 52, and the movable upper ends oi thereset levers 55 are coupled by slidable links 51 to opposite ends of thepin 33 which is carried by the actuating plate 32.

Referring now particularly to Figs. 2, 3, 4 and 5, the manual andautomatic operation 01' my new and improved circuit breaker will beclear from the following brief description.

At Fig. 5 the mechanism is shown in the manual open position. Thecontacts may be closed manually by depressing the push button 33,thereby to rotate the rocker arms 35 in a clockwise direction, as viewedin the drawings, about the pivot pin 23.

When the rocker arms are thus rotated the lower edges of the open-endedslots 31 in the rocker arms engage the transverse pin 33 on the plate 32in such a position that the pin is forced to slide inwardly in the slots31 thereby to move the actuating plate 32 by camming action about itsfixed pivot 33 in a clockwise direction, as viewed in the drawings. Theapertures 31a in the rocker arms 35 simply accommodate the transversepin 3! and allow freedom of movement of the actuating plate 32. Thecamming action between the pin 38 andthe slots 31 produces a relativelylarge angular movement of the actuating lever 32 as a result of smallangular movement of the rocker levers 35.

When the plate 32 moves in a clockwise direction it carries with it theattached pin 3i, to the ends of which are attached the toggle springs30. toggle springs is moved over. center with respect to the fixed pivot26, so that the toggle links are biased to the op osite side of thepivot 28. The toggle links 25 therefore move in a counterclockwisedirection about the fixed pivot 28 and straighten the toggle links 21,thereby to force the pivoted switch member 2| downwardly and close thecontacts. After this operation is completed the breaker mechanism is inthe position shown at Fig. 2 of the drawing.

It will, of course, be understood that manual opening operation issimply the reverse of the closing operation described above. Referringto Fig. 2 the breaker contacts are opened by depressing the push button360: and thus rotating the rocker arms about the fixed pivot 2t in acounter-clockwise direction. In so moving the upper edges of theopen-ended slots 3i in the rocker arms 35 engage the transverse pin insuch a position that the pin 35 is forced to slide outwardly along theslots til, thereby to rotate the actuating plate in a counterclockwisedi- 0s. rection about its fixed pivot 33. Such counter clockwisemovement of the actuating plate 32 L carries the pin 3i and the togglesprings til over center with respect to the fixed pivot and thus breaksthe toggle to the position shown at Fig. 5.

Assuming now that the mechanism is in the manual closed position shownat "Fig. 2, an autci'natic tripping operation upon the occurrence of anexcessive current takes place as follows: Upon the occurrence of apredetermined excessive current the thermal strip til is heated anddeformed in such a direction that the trip lever I. is moved slowly in aclockwise direction, as viewed at Fig. 5. As soon as the trip lever iii?is carried over center the trip lever continues in movement with a snapaction under the influence of its over-center spring t l. thereby tobring the inwardly extending arm of the trip lever into strikingengagement with the second latch lever M. The latch lever iills thusmoved in a clockwise direction, as viewed in the drawlugs, against thebias of the latch spring it and to a position to release the latch leverit. When the latch lever 42 is released by the latch lever 44 the latchspring 45 rotates the lever 42 in a counterclockwise direction, asviewed in the drawings, thereby to release the latched end of the triplever 40.

Upon release of the trip lever 40 the spring ll forcibly rotates themember All in a clock" wise direction and brings it into strikingengagement with the toggle pin 28. The toggle pin 28 is thus forced tomove to the left, as viewed at Fig. 3, thus breaking the toggle andmoving the toggle springs 30 over-center with respect to the fixed pivot26. This movement of the toggle springs 30 carries the actuating In thismanner the line of action 0! the plate 32 to a mid-position, asillustrated at Fig. 3. In moving to such mid-position the plate 32 bycamming action moves the rocker levers 35 to a mid-position. so that inthe trip position of the breaker mechanism the push buttons 36 and 38aare also in a mid-position. This positioning of the push buttons servesas an indication of the tripped condition of the mechanism.

In order to reset the breaker mechanism after an automatic trippingoperation such as that described above, the rocker arms 35 must be movedin a counterclockwise direction beyond their manual open" position bydepression of the push button 38a. The "reset position of the mechanismis shown at Fig. 4; and by com- Darison with Fig. 5 it may be seen thatin resetting operation the camming pin 38 on the actuating plate 32 ismoved by the rocker arms 35 to an extreme outward position in the slots31; that is, the actuating plate 32. is rotated to an extremecounterclockwise position. In moving to this position the pin 38 on theplate 32 presses against the upper arm of the pivoted trip member 40 androtates the trip member in a counterclockwise direction against the biasoi the spring 4i and beyond its normal latched position. As clearlyshown at Fig. 4 extreme counterclockwise or resetting movement of thetrip member iil'causes the normally latched end of the trip member toengage the lower arm 42a of the latch lever it, thereby to rotate thelatch lever M2 in a clockwise direction to its latching position. Inmoving to this position the latch lever i2 stresses the latch spring (i5and thus biases the second latch lever i i to its latched position shownat Fig. 5. As pointed out previ ously, however, the second latch leverto cannot move to this position until the trip levers ll? on theovercurrent tripping mechanisms lit are first reset by operation of thereset levers During the resetting movement of the breaker mechanism thereset levers till are rotated in a counterclockwise direction by the pinon the plate 322. As the pin 38 is moved to its extreme counterclockwiseor reset position it carries with it the reset levers 55, slight Slidingmove ment of the pin 38 with respect to the levers being allowed by theslidable links Thus during the resetting movement the reset leversrotate counterclockwise and engage the tripping arms thereby to forcethe tripping levers over center to their normal positions as shown atFigs. 1, Z and 5. With the tripping levers 52 thus removed from the pathof the latch lever i l by operation of the reset levers 55, the latchlever i l resets itself under the influence of the latching spring d5 sothat the mechanism assumes the position'shown at Fig. 4. When the pushbutton tile is released, the tension spring ii returns the trip memberill to its normal latched position shown at Fig. 2 by a slight clockwisemovement. Such clockwise return movement of the trip lever it causes aslight clockwise return movement of the actuating plate 32 to the manualopen position shown in Fig. 5, and by camming movement of the pin 35!against the slots 31 the rocker arms 35 are moved slightly clockwise tothe manual open position. All parts are now fully reset to the openposition shown at Fig. 5 and prepared for manual operation to close thebreaker.

While I have described but a single preferred embodiment of my inventionby way of illustration, many modifications will occur to those skilledin the art. For example, while I have illustrated sired number or switchcontacts and may be combined with any desired number of independentover-current tripping mechanisms. I therefore wish to have it understoodthat I intend in the appended claim to cover all such modifications asfall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent 01 the UnitedStates, is:

A circuit breaker comprising a switch member movable between open andclosed circuit positions, an over-center toggle mechanism connected tomove said switch member and including a toggle spring having one endconnected to the knee of said toggle, an actuating plate pivotallymounted at a first fixed point and having a movable point thereofconnected to the other end of said spring thereby to control said togglemechanism, a rocker arm pivotally mounted intermediate its ends at asecond fixed point disposed between the pivoted and movable points ofsaid actuating plate, said rocker arm being disposed transversely of aline between said pivoted and movable points, and a camming pin fixedlymounted on said actuating plate and laterally displaced i'rom said line,said rocker arm being slotted at one side of its pivot point along a,line generally tangential to a circle through said first fixed point andsaid camming pin being slidabl disposed in said slot, wherebyoscillation of said rocker arm about said second fixed point effectsamplified angular movement of said actuating plate about said firstfixed point.

WILLIAM LAWRENCE BUTLER.

REFERENCES CITED The following rei'erenices are or record in the tile orthis patent:

UNITED STATES PATENTS 80 Number Name Date 66,360 King July 2, 18671,246,646 Pape Nov. 13, 1917 2,230,713 Butler Feb. 4, 1941 2,258,232Atwood et a1. Oct. 7, 1941 26 2,357,210 Leonard Aug. 29 1944

